Mounting structure for movable cutting blade



Oct. 30, 1962 J. F. WAHL 3,060,570

MOUNTING STRUCTURE FOR MOVABLE CUTTING BLADE Filed March 4, 1959 Era, 1 FIG :7 l0

liLi Lmiff'gg INVENTOR.

John F WahZ 3,060,570 Patented Oct. 30, 1962 3,069,570 MOUNTING STRUCTURE FGR MOVABLE CUTTING BLADE John F. Wahl, Sterling, Ill., assignor to Wahl Clipper Corporation, Sterling, Ill., a corporation of Illinois Filed Mar. 4, 1959, Ser. No. 797,097 7 Claims. (ill. Sid-43) This invention relates to an electric shaver, and more particularly to a mounting structure for the movable cutting blade of the shaver.

In electric shavers of the kind driven by vibratory electric motors, a drive finger is connected at one end to the vibrating armature and at the other end to a movable cutting blade in a manner well known in the art. Recent improvements in electric shavers have led to the development of a shaver with an inner movable cutting blade made from thin pre-hardened sheet metal which is formed into a cylindrical, tubular shape.

These shavers are generally provided with a fixed outer blade, also formed from thin pre-hardened sheet metal and the bearing contact between the movable inner blade and the fixed outer blade is critical. Any deformations present on the periphery of the inner movable blade could affect this bearing contact, and this would adversely affect the operation of the shaver.

One end of the drive finger of the motor is connected to the movable cutting blade described above in order to cause it to oscillate. This connection can not be a direct one because the thin sheet metal of the blade would not be sufiiciently durable for that purpose. What is needed therefore and comprises an important object of this invention is to provide a mounting structure for the movable cutting blade which can make a durable connection with the drive finger of the vibratory motor and which can be easily connected to the movable cutting blade.

It would be desirable to lock the movable cutting blade in its exact final form before it is installed on the shaver, and it would be economically useful to design the mounting structure so it also provides this added function. What is needed therefore and comprises still another object of this invention is a mounting structure for a movable cutting blade which can make a durable connection with the drive finger of a vibratory motor and which can also hold the movable cutting blade in its final cylindrical form before it is installed on the shaver.

In addition, since electric shavers are frequently used in wash rooms, it is essential that the metallic blades which contact the skin be completely insulated from the electric motor inside the shaver and from any other electrically conductive parts on the shaver to eliminate the possibility of dangerous electric shocks. What is needed therefore and comprises still another object of this invention is a mounting structure for a movable cutting blade which is formed from an insulating material and which acts to electrically insulate the movable cutting blade from any electrical partin the motor.

Another object of this invention is to provide a low friction support and bearing surface for the movable cutting blade.

Still a further object of this invention is to provide a noiseless driving connection between the movable cutting lade and the driving finger.

Yet another object of this invention is to provide a support for a movable cutting blade which will allow it to flex.

These and other objects of this invention will become more apparent when read in the light of the accompanying drawings and specification wherein:

FIG. 1 is a plan view of an electric shaver body (cover removed) with the movable cutting blade and its mounting structure positioned thereon.

RIG. 2 is a plan view of the movable cutting blade before it is curved to its tubular shape.

FIG. 3 is an end elevational view of an illustrative movable cutting blade after it is curved to its initial arcuate tubular shape.

FIG. 4 is an end elevational view of the movable cutting blade and mounting structure in a form ready for installation on the shaver.

FIG. 5 is a sectional view on the line 55 of FIG. 4.

FIG. 6 is a side elevational view of parts of the mount ing structure for the movable cutting blade in exploded form.

FIG. 7 is a portion of a plan view of an electric shaver with a modified mounting structure.

FIG. 8 is a perspective view of the base member of the modified mounting structure showing in addition a modified drive finger.

Referring now to FIG. 1 of the drawings, an electric shaver indicated generally by the reference numeral 19 comprises a casing 12 in which an electric vibratory motor 14- is mounted. Armature it; of the motor is connected to end 17 of a drive finger 18. The other end 19 of the drive finger is connected to the movable cutting blade indicated generally by the reference numeral Zll.

The movable cutting blade 2t) includes an initially flat pre-hardened piece of resilient sheet metal 22 and a mounting structure 24 (FIGS. 4-6). The sheet metal FIG. 2) has parallel sides and ends 26 and 28. In addition it has a central perforate cutting region 30 and ro'ectin member receivin o enin s 32. These 0 enings are divided into groups 34 and 36 adjacent the opposed ends 28 of the sheet metal. In the particular embodiment disclosed in the drawing there are two openings in each group disposed along a straight straight line indicated by dotted lines 33. The lines 33 connecting the openings in each group are parallel to each other and the common lines 35 connecting corresponding openings in each group are parallel to each other so that the openings 32 may be described as being located on the corners of a rectangle. This is not an essential arrangement and it is contemplated that the sheet metal could have more than two groups of openings, and each group could contain more than two openings, and the openings could be disposed along any predetermined path, so long as the openings in each group have the same spatial distribution. With this arrangement, the corresponding openings in each group will still be disposed along a common line and the common lines connecting the corresponding openings in each group will still be parallel to each other.

The sheet metal is continuously curved by any suitable means around a line perpendicular to the parallel sides 26 and to the common lines 35 connecting the corresponding openings in each group until the ends 23 overlap each other, see FIG. 3. The curvature is such that when all the corresponding openings in each group are aligned with each other, the sheet metal will have the desired tubular substantially cylindrical form required for good bearing contact with the fixed outer blade, see FIG. 4.

To hold the sheet metal in this tubular cylindrical form, the mounting structure 24 in the embodiment of FIG. 1 includes a base member 4! and a locking bar 42 both formed from an insulating thermoplastic material, such as molded nylon.

The base member in this particular embodiment is substantially rectangular in cross-section and has two spaced parallel cylindrical projecting members 44 perpendicular to surface 46 and extending out therefrom. Surface 48 opposite to surface 46 is provided with a groove 50 which is positioned centrally between the projections and perpendicular to a line connecting them. This groove is V- shaped in cross section with the walls defining an angle of about 30 and is designed to pivotally receive the free end 19 of the drive finger 18 of motor 14, see FIG. 5. This pivotal connection is necessary because the vibrating armature 16 causes the free end 19 of the drive finger to oscillate along a slightly arcuate path while the surface 48 of base member 4-0 is constrained to move in a straight line because of a planar guideway 49 on the body of the shaver, see FIG. 1. The connection between drive finger 18 and base member 40 is much more durable than a direct connection between the free end of the drive finger and the sheet metal 22 would be because the sheet metal is so thin that the continual vibratory forces applied to it by the free end of the drive finger would destroy the connection in a short time.

Locking bar 42, as seen in FIG. 4, has a cylindrical surface 52 and an opposed planar surface 54, but the shape of surface 54 is not critical. This locking bar is provided with spaced openings 56, see FIG. 6. In this embodiment, openings 56 extend completely through the bar, and although this arrangement is very desirable, under some conditions it may be desirable for openings 56 to extend only part way through the locking bar.

Openings 56 are spaced apart a distance equal to the spacing between projections 44 and the spacing between the aligned openings in the tubular cylindrical sheet metal, see FIGS. and 6. In addition, the openings 56 in bar 42 are sized to receive and frictionally grip the projections 44 on the base member so that the base member and locking bar may be securely held together. It is to be understood that the projecting members 44 could extend from locking bar 42 and the base member 40 could have the openings 56 extending therein, and the claims should be construed to include this reversal of parts.

To attach the mounting structure 24 to the sheet metal 22, the ends of the curved sheet metal are moved so that openings 32 in groups 34 and 36 are in alignment with each other. Then the projecting members 44 of the base member 40 are inserted in these openings to retain the sheet metal in its tubular cylindrical form. Next the locking bar is inserted in the tubular element with its arcuate cylindrical surface 52 engaging the inner surface of the cylindrical tube and openings 56 aligned with projections 44 extending into the cylindrical tube. Next the base member 49 and locking bar 42 are forced together with the projections 44- extending completely through openings 56, see FIG. 4. This arrangement is advantageous because the base member and locking bar can be forced tightly together compressing a substantial part of the walls of the cylindrical tube between them. Since surface 52 of the locking bar 42 is itself cylindrical, when the base member and the locking bar are forced together in this manner, surface 52 acting as a sort of die forces the compressed part of the walls to assume a more exact cylindrical shape, thereby correcting minor deformations in the periphery of the cutting blade and locking the mounting structure 24 to the curved sheet metal 22. It may not be desirable to rely on the frictional grip between the projections 44 and openings 56 to hold them together. In such a case both the base member and the locking bar are formed from a thermoplastic material. Heat may be applied to the projections in the openings to cause them to be welded together. It is understood that only one of these two elements need to be made of a thermoplastic material and the claims should be construed accordingly.

FIGS. 7 and 8 disclose an electric shaver with a modified mounting structure. In this modification, the inner movable cutting blade is mounted on a mounting structure which includes the modified base member 40. Base member 40' differs from base member 40 shown in the embodiment in FIG. 1 in that it is provided with a laterally projecting T-bar 60, rendering groove 50 unnecessary. The T-bar is located on end 62 of the base member 40 and is adapted to be connected to the end 19' of the modified drive finger 18'. End 19' is slotted at 64 so it can receive the stem 66 of the T-bar.

Another advantage gained through the use of the modified arrangement shown in FIGS. 7 and 8 is that the drive finger 18 can be inserted through some flexible material 68 such as sponge which offers little resistance to the vibration of the drive finger, but which effectively seals off the interior of the shaver from the entrance of objectionable hair fragments.

It is understood that the modified base member 40 does not require any change in the locking bar 42, so that in other respects, the movable cutting blade in this modification is identical with the one shown in the modification of FIG. 1.

With the movable cutting blade constructed as described, it can be conveniently examined for defects prior to installation on the body of the shaver. Also the operator of the shaver will be protected from electric shocks by the molded nylon, Teflon, or other insulating material forming the mounting structure of the blades. In addition the use of molded nylon for the mounting structure contains the additional advantages of lightness and strength combined with quietness of operation and low sliding friction.

The invention may be embodied in other forms without departing from the spirit or essential characteristics thereof as set forth in the claims and the present embodiment is therefore to be considered as illustrative and not restrictive and it is intended to include all changes which come within the scope and range of the claims.

I claim:

1. A cutter for a tool comprising:

a piece of resilient sheet metal curved to tubular shape and having end portions thereof overlapping;

said overlapping end portions having aligned openings therethrough;

a base member; and

projecting means on said base member extending through said aligned openings whereby said sheet metal piece is retained in tubular shape.

2. The combination of claim 1 with the addition of a locking member secured to said projecting means on the side of said overlapping end portions opposite said base member.

3. The combination of claim 2 wherein the surface of said locking member facing said overlapping end portions is a cylindrical segment, said surface bearing against one of said overlapping end portions and imparting cylindrical shape thereto.

4. A cutting element for an electric shaver comprising:

a piece of resilient sheet metal having perforations in its central region, said piece curved to tubular cylindrical shape and having end portions thereof overlapping;

said overlapping end portions having spaced pairs of aligned openings therethrough;

a base member; and

projecting means on said base member extending through said aligned openings whereby said sheet metal piece is retained in tubular cylindrical shape.

5. The combination of claim 4 wherein the surface of said base member opposite said projecting means is a flat "bearing surface adapted to engage a cooperating bearing surface.

6. A cutting element for an electric shaver comprising:

a piece of resilient sheet metal having a central perforate cutting portion and two spaced projection member receiving openings at each end, said openings located at the corners of a rectangle, said piece curved with its ends overlapping whereby the openings at one end are aligned with the openings at the other end and said piece has tubular, substantially cylindrical form;

a base member; and

two projecting members extending from said base member and spaced apart a distance equal to the separation of said aligned openings and extending through said openings, said base member having a recess adapted for engagement *by a drive means.

7. The combination of claim 6 with the addition of means for holding said projecting members in said aligned openings, said means comprising a bar positioned inside said cylindrical piece and having two spaced openings sized to receive and frictionally hold said projecting members, said openings spaced apart a distance equal to the spacing of said projecting members.

References Cited in the file of this patent UNITED STATES PATENTS 348,330 LaFave Aug. 31, 1886 6 Rand et a1. Oct. 11, Wimberger Nov. 21, Bruecker Dec. 5, Sussman May 20, Wright Nov. 18, NeWhouse Sept. 5, Ritter Oct. 4, Ranson Dec. 11, Heyek Aug. 13, Lussier Jan. 14, Padgett July 8, Braun et al. Oct. 20,

FOREIGN PATENTS Great Britain Oct. 17, 

